Identifying Rear Calipers

[2052006 10]

I can't remember whether I used standard 1.9 rear calipers, when I did the disc conversion on the rear several years ago, or later 306 type calipers - which would have a 32mm piston, rather than a 30mm. What is the easiest way of identifying which I have. The obvious answer is obvious, I know: measure the pistons. However, what part am I supposed to measure? The "end" of the piston (which pushes against the pad) - ? That is 30mm, as far as I can see. However, the rest of the piston (the part that slides in and out of the caliper) seems to be wider.

 

So which part should I be measuring?

 

As a side note, I do know for sure that I am using 306 rear hubs, if this makes any difference. I assume both 30mm and 32mm caliper will fit these hubs?

 

 

[welshpug 1,658]

Pop the piston dust cover off and check the o.d there, the part against the pad is always 30mm